uniq(1) General Commands Manual uniq(1)
Name
uniq - report repeated lines in a file
Syntax
uniq [-udc[+n][-n]] [input[output]]
Description
The command reads the input file comparing adjacent lines. In the normal case, the second and succeeding copies of repeated lines are
removed; the remainder is written on the output file. Note that repeated lines must be adjacent in order to be found. For further infor-
mation, see
Options
The n arguments specify skipping an initial portion of each line in the comparison:
-n Skips specified number of fields. A field is defined as a string of non-space, non-tab characters separated by tabs and spaces from its
neighbors.
+n Skips specified number of characters in addition to fields. Fields are skipped before characters.
-c Displays number of repetitions, if any, for each line.
-d Displays only lines that were repeated.
-u Displays only unique (nonrepeated) lines.
If the -u flag is used, just the lines that are not repeated in the original file are output. The -d option specifies that one copy of
just the repeated lines is to be written. The normal mode output is the union of the -u and -d mode outputs.
The -c option supersedes -u and -d and generates an output report in default style but with each line preceded by a count of the number of
times it occurred.
See Also
comm(1), sort(1)
uniq(1)
